Elucidation of a bacterial pathway for catabolism of the β–β-linked dilignol pinoresinol
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- University of Wisconsin, Madison, WI (United States)
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Oregon State University, Corvallis, OR (United States)
- Washington State University, Pullman, WA (United States)
- University of British Columbia, Vancouver, BC (Canada)
Monolignol-derived dimers containing β–β linkages are synthesized by vascular plants and can be released during lignin depolymerization. In this work, we isolated a bacterium, Novosphingobium rhizosphaerae LY, that grows with the β–β lignan (+)-pinoresinol as a sole growth substrate. Sequence analysis suggested that this strain encodes a broad range of pathways for assimilation of aromatic monomers as well as one enzyme implicated in pinoresinol catabolism but lacks other known pathways for aromatic dimer catabolism. We constructed a genome-wide barcoded transposon library and identified genes required for pinoresinol catabolism. Using feeding studies, compound isolation, targeted synthesis, and analysis of purified enzymes, we elucidated the biochemical intermediates and reaction pathway involved in pinoresinol catabolism. We demonstrated that the first enzymatic reaction is the reductive cleavage of a furan ring in (±)-pinoresinol with retention of configuration to yield lariciresinol. We additionally confirmed that the final pathway enzyme, PinU, is related to lignostilbene dioxygenases and oxidatively cleaves a diguaiacylbutadiene intermediate to yield vanillin and coniferaldehyde. Finally, based on the enzyme characterization, we demonstrated that the strain can grow with a second β–β lignan, (–)-syringaresinol, as a sole growth substrate. In combination, these results demonstrate a new biocatalytic route for transforming a widely occurring group of plant phenylpropanoid natural products.
- Research Organization:
- Great Lakes Bioenergy Research Center (GLBRC), Madison, WI (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- SC0018409; AC05-00OR22725
- OSTI ID:
- 2589405
- Alternate ID(s):
- OSTI ID: 3002895
- Journal Information:
- mBio (Online), Journal Name: mBio (Online) Journal Issue: 11 Vol. 16; ISSN 2150-7511
- Publisher:
- American Society for Microbiology (ASM)Copyright Statement
- Country of Publication:
- United States
- Language:
- English